In the food industry, systems of conveyors are used to transport goods containers from machine to machine to process them before they are shipped to distributors. Often, machinery is needed to reorient the containers as they are conveyed to and from the various processing machines to properly arrange them for upcoming machines. For instance, in the beverage industry, cases of beverage cans or bottles are typically conveyed from machine to machine in a lengthwise orientation, i.e., with the length dimension of the case parallel to its direction of travel along the conveyor. At times, however, the cases must be rotated ninety degrees such that the lengths of the cases are perpendicular to the direction of travel. For example, with some shrink-wrap machines, widthwise orientation permits greater productivity by increasing the number of cases that can be wrapped in a given period of time.
Several different turning methods have been used in the past to effect such ninety degree rotation of containers. Under one such method, the container is transported to a straight section of conveyor having two parallel conveyor belts separated by an elongated intermediate steel plate. The conveyor section is sized and configured such that each of the outer portions of the container rests upon one of the conveyor belts. In operation, the two conveyor belts are operated at different speeds to transport the container along the conveyor section. However, since the two belts are running at different speeds, the outer portion of the container that is resting upon the faster conveyor belt is pulled ahead of the opposite outer portion, causing the box to rotate about its centeral axis.
To function properly, the length of the conveyor section, speed of the two conveyor belts, and weight of the container must be taken into account to ensure that after the container has traversed the full length of the conveyor section, it will have been rotated ninety degrees. Although capable of functioning adequately under optimal operating conditions, double belt turning conveyors such as that described above tend to malfunction when such conditions are less than ideal. In particular, variations in temperature, humidity, container weight, and container material can each individually vary the frictional forces acting on the containers, causing them to be improperly rotated.
When improper rotation occurs, the common result is a conveyor jam. In that the production line must be halted with each such jam, these conveyor jams reduce productivity, delay production, and increase operation costs. Exacerbating these negative effects is the fact that once the jam is cleared, the cause of the jam must be determined and remedied to prevent new jams, further increasing production line down-time and increasing costs. In addition to creating these problems, double belt turning conveyors are long (typically about 12 feet in length) and therefore require substantial plant space that could be used for other purposes. This space requirement can create difficulty in situations in which such space is limited or unavailable.
In another common turning device, a pinwheel-shaped gate device is used to rotate containers. With such an arrangement, the gate device has a body portion through which its central axis is located. Extending outwardly in four directions, each separated by ninety degrees from the next, are gate arms. In use, a container engages the gate arm that extends across the path of the conveyor belt upon which the container rests. A photo eye senses the arrival of the container and signals a brake, which holds the gate device in position, to release causing the gate device to rotate about its central axis under the urging of the moving container. As the gate device turns, it acts as a turn/stile and causes the container to likewise rotate about the central axis of the gate device. After the container has rotated ninety degrees, and is therefore reoriented on the conveyor, the photo eye senses that the container has passed and sends a signal for the brake of the gate device to re-engage in preparation for the next container.
Gate devices of the type described above have been successfully operated in prior art systems. However, the design of these devices is complicated by moving parts and expensive electronic sensing and control devices. Accordingly, these gate devices are more expensive to purchase, operate, and maintain. Moreover, to avoid jamming of the gate device, the containers cannot be rotated quickly, thereby reducing productivity.
From this discussion it can be appreciated that it would be desirable to have a device for turning containers through ninety degrees which is both simple and inexpensive. Additionally, it would be desirable to have such a device which operates quickly and in small spaces such that high efficiency in both production and plant space optimization are maintained.